The present invention relates generally to the field of automated stacking machines, and, more particularly, to stacking machines that use compression and can use compensation in forming the stacks.
For mass production of printed media, stacking machines are used to organize, count, stack, compress and package product such as magazines, newspapers, newspaper supplements, flyers, and press signatures for shipment. These machines typically include a feeder or supply component comprising a conveyor system for receiving product to be stacked. Next, through a combination of conveyors and mechanical apparatus, the products are organized into stacks, which are then compressed for shipment as they exit the machine. For maximum stability of the compressed stacks, compensation is often used in which stack portions are alternately rotated 180.degree. during compression to counteract any tendency or bias to lean in a specific direction.
While existing stacking machines are useful for their intended purposes, they are accompanied with several drawbacks: First, misshapen or misaligned product are prone to jam inside the machines resulting in lost production time and sometimes requiring disassembly of the machine to free the jam. Second, existing machines use plates, rollers or similar devices to move belts in and out to align product, which is ineffective in some applications. Third, when changing product lines, existing machines frequently require adjustments to the conveyor belt assembly to accommodate a new product size. These adjustments can be time consuming and potentially result in more product jams inside the machine if the adjustments are inaccurate. Fourth, the stacking apparatus used by existing machines is often inefficient by requiring a product stack portion or lift to be filled and expelled from the machine before the stacking apparatus is ready to receive more product. Fifth, although compression of the product is a critical factor in minimizing space and maximizing stability in shipping, most existing stacking machines are designed to provide only one or no application of compression to the product, particularly at high speed. Finally, existing stacking machines, due to their location of the product counter, do not consistently give accurate product quantities per lift or stack portion.
Accordingly, there exists a need for an improved compensating stacking machine that reduces jams resulting from entry of misshapen or misaligned product. Furthermore, it is desirable that maximum product alignment be achieved through the use of belt joggers. It is also desirable that the compensating stacking machine accommodate multiple product lines with a minimum of adjustments when switching between lines. Additionally, it is desirable that the stacking machine provide an improved stacking assembly capable of processing more than one lift or stack portion at a time and that each lift, stack portion, or product stack is compressed at least once and preferably more than once. For uniformity in lift size and quantity, it is desirable to attain an accurate count of product before forming the lift.